JavaScript - GPS Bricklet

This is the description of the JavaScript API bindings for the GPS Bricklet. General information and technical specifications for the GPS Bricklet are summarized in its hardware description.

An installation guide for the JavaScript API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Simple (Node.js)

Download (ExampleSimple.js)

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var Tinkerforge = require('tinkerforge');

var HOST = 'localhost';
var PORT = 4223;
var UID = 'XYZ'; // Change XYZ to the UID of your GPS Bricklet

var ipcon = new Tinkerforge.IPConnection(); // Create IP connection
var gps = new Tinkerforge.BrickletGPS(UID, ipcon); // Create device object

ipcon.connect(HOST, PORT,
    function (error) {
        console.log('Error: ' + error);
    }
); // Connect to brickd
// Don't use device before ipcon is connected

ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
    function (connectReason) {
        // Get current coordinates
        gps.getCoordinates(
            function (latitude, ns, longitude, ew, pdop, hdop, vdop, epe) {
                console.log('Latitude: ' + latitude/1000000.0 + ' °');
                console.log('N/S: ' + ns);
                console.log('Longitude: ' + longitude/1000000.0 + ' °');
                console.log('E/W: ' + ew);
            },
            function (error) {
                console.log('Error: ' + error);
            }
        );
    }
);

console.log('Press key to exit');
process.stdin.on('data',
    function (data) {
        ipcon.disconnect();
        process.exit(0);
    }
);

Callback (Node.js)

Download (ExampleCallback.js)

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var Tinkerforge = require('tinkerforge');

var HOST = 'localhost';
var PORT = 4223;
var UID = 'XYZ'; // Change XYZ to the UID of your GPS Bricklet

var ipcon = new Tinkerforge.IPConnection(); // Create IP connection
var gps = new Tinkerforge.BrickletGPS(UID, ipcon); // Create device object

ipcon.connect(HOST, PORT,
    function (error) {
        console.log('Error: ' + error);
    }
); // Connect to brickd
// Don't use device before ipcon is connected

ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
    function (connectReason) {
        // Set period for coordinates callback to 1s (1000ms)
        // Note: The coordinates callback is only called every second
        //       if the coordinates has changed since the last call!
        gps.setCoordinatesCallbackPeriod(1000);
    }
);

// Register coordinates callback
gps.on(Tinkerforge.BrickletGPS.CALLBACK_COORDINATES,
    // Callback function for coordinates callback
    function (latitude, ns, longitude, ew, pdop, hdop, vdop, epe) {
        console.log('Latitude: ' + latitude/1000000.0 + ' °');
        console.log('N/S: ' + ns);
        console.log('Longitude: ' + longitude/1000000.0 + ' °');
        console.log('E/W: ' + ew);
        console.log();
    }
);

console.log('Press key to exit');
process.stdin.on('data',
    function (data) {
        ipcon.disconnect();
        process.exit(0);
    }
);

Simple (HTML)

Download (ExampleSimple.html), Test (ExampleSimple.html)

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<!DOCTYPE html>
<html>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <head>
        <title>Tinkerforge | JavaScript Example</title>
    </head>
    <body>
        <div style="text-align:center;">
            <h1>GPS Bricklet Simple Example</h1>
            <p>
                <input value="localhost" id="host" type="text" size="20">:
                <input value="4280" id="port" type="text" size="5">,
                <input value="uid" id="uid" type="text" size="5">
                <input value="Start Example" id="start" type="button" onclick="startExample();">
            </p>
            <p>
                <textarea readonly id="text" cols="80" rows="24" style="resize:none;"
                          >Press "Start Example" to begin ...</textarea>
            </p>
        </div>
        <script src="./Tinkerforge.js" type='text/javascript'></script>
        <script type='text/javascript'>
            var ipcon;
            var textArea = document.getElementById("text");
            function startExample() {
                textArea.value = "";
                var HOST = document.getElementById("host").value;
                var PORT = parseInt(document.getElementById("port").value);
                var UID = document.getElementById("uid").value;
                if(ipcon !== undefined) {
                    ipcon.disconnect();
                }
                ipcon = new Tinkerforge.IPConnection(); // Create IP connection
                var gps = new Tinkerforge.BrickletGPS(UID, ipcon); // Create device object
                ipcon.connect(HOST, PORT,
                    function(error) {
                        textArea.value += 'Error: ' + error + '\n';
                    }
                ); // Connect to brickd
                // Don't use device before ipcon is connected

                ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
                    function (connectReason) {
                        // Get current coordinates
                        gps.getCoordinates(
                            function (latitude, ns, longitude, ew, pdop, hdop, vdop, epe) {
                                textArea.value += 'Latitude: ' + latitude/1000000.0 + ' °\n';
                                textArea.value += 'N/S: ' + ns + '\n';
                                textArea.value += 'Longitude: ' + longitude/1000000.0 + ' °\n';
                                textArea.value += 'E/W: ' + ew + '\n';
                            },
                            function (error) {
                                textArea.value += 'Error: ' + error + '\n';
                            }
                        );
                    }
                );
            }
        </script>
    </body>
</html>

Callback (HTML)

Download (ExampleCallback.html), Test (ExampleCallback.html)

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<!DOCTYPE html>
<html>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <head>
        <title>Tinkerforge | JavaScript Example</title>
    </head>
    <body>
        <div style="text-align:center;">
            <h1>GPS Bricklet Callback Example</h1>
            <p>
                <input value="localhost" id="host" type="text" size="20">:
                <input value="4280" id="port" type="text" size="5">,
                <input value="uid" id="uid" type="text" size="5">
                <input value="Start Example" id="start" type="button" onclick="startExample();">
            </p>
            <p>
                <textarea readonly id="text" cols="80" rows="24" style="resize:none;"
                          >Press "Start Example" to begin ...</textarea>
            </p>
        </div>
        <script src="./Tinkerforge.js" type='text/javascript'></script>
        <script type='text/javascript'>
            var ipcon;
            var textArea = document.getElementById("text");
            function startExample() {
                textArea.value = "";
                var HOST = document.getElementById("host").value;
                var PORT = parseInt(document.getElementById("port").value);
                var UID = document.getElementById("uid").value;
                if(ipcon !== undefined) {
                    ipcon.disconnect();
                }
                ipcon = new Tinkerforge.IPConnection(); // Create IP connection
                var gps = new Tinkerforge.BrickletGPS(UID, ipcon); // Create device object
                ipcon.connect(HOST, PORT,
                    function(error) {
                        textArea.value += 'Error: ' + error + '\n';
                    }
                ); // Connect to brickd
                // Don't use device before ipcon is connected

                ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
                    function (connectReason) {
                        // Set period for coordinates callback to 1s (1000ms)
                        // Note: The coordinates callback is only called every second
                        //       if the coordinates has changed since the last call!
                        gps.setCoordinatesCallbackPeriod(1000);
                    }
                );

                // Register coordinates callback
                gps.on(Tinkerforge.BrickletGPS.CALLBACK_COORDINATES,
                    // Callback function for coordinates callback
                    function (latitude, ns, longitude, ew, pdop, hdop, vdop, epe) {
                        textArea.value += 'Latitude: ' + latitude/1000000.0 + ' °\n';
                        textArea.value += 'N/S: ' + ns + '\n';
                        textArea.value += 'Longitude: ' + longitude/1000000.0 + ' °\n';
                        textArea.value += 'E/W: ' + ew + '\n';
                        textArea.value += '\n';
                        textArea.scrollTop = textArea.scrollHeight;
                    }
                );
            }
        </script>
    </body>
</html>

API

Generally, every method of the JavaScript bindings can take two optional parameters, returnCallback and errorCallback. These are two user defined callback functions. The returnCallback is called with the return values as parameters, if the method returns something. The errorCallback is called with an error code in case of an error. The error code can be one of the following values:

  • IPConnection.ERROR_ALREADY_CONNECTED = 11
  • IPConnection.ERROR_NOT_CONNECTED = 12
  • IPConnection.ERROR_CONNECT_FAILED = 13
  • IPConnection.ERROR_INVALID_FUNCTION_ID = 21
  • IPConnection.ERROR_TIMEOUT = 31
  • IPConnection.ERROR_INVALID_PARAMETER = 41
  • IPConnection.ERROR_FUNCTION_NOT_SUPPORTED = 42
  • IPConnection.ERROR_UNKNOWN_ERROR = 43
  • IPConnection.ERROR_STREAM_OUT_OF_SYNC = 51

The namespace for the JavaScript bindings is Tinkerforge.*.

Basic Functions

new BrickletGPS(uid, ipcon)
Parameters:
  • uid -- string
  • ipcon -- IPConnection

Creates an object with the unique device ID uid:

var gps = new BrickletGPS("YOUR_DEVICE_UID", ipcon);

This object can then be used after the IP Connection is connected (see examples above).

BrickletGPS.getCoordinates([returnCallback][, errorCallback])
Callback:
  • latitude -- int
  • ns -- char
  • longitude -- int
  • ew -- char
  • pdop -- int
  • hdop -- int
  • vdop -- int
  • epe -- int

Returns the GPS coordinates. Latitude and longitude are given in the DD.dddddd° format, the value 57123468 means 57.123468°. The parameter ns and ew are the cardinal directions for latitude and longitude. Possible values for ns and ew are 'N', 'S', 'E' and 'W' (north, south, east and west).

PDOP, HDOP and VDOP are the dilution of precision (DOP) values. They specify the additional multiplicative effect of GPS satellite geometry on GPS precision. See here for more information. The values are give in hundredths.

EPE is the "Estimated Position Error". The EPE is given in cm. This is not the absolute maximum error, it is the error with a specific confidence. See here for more information.

This data is only valid if there is currently a fix as indicated by getStatus().

BrickletGPS.getStatus([returnCallback][, errorCallback])
Callback:
  • fix -- int
  • satellitesView -- int
  • satellitesUsed -- int

Returns the current fix status, the number of satellites that are in view and the number of satellites that are currently used.

Possible fix status values can be:

Value Description
1 No Fix, getCoordinates(), getAltitude() and getMotion() return invalid data
2 2D Fix, only getCoordinates() and getMotion() return valid data
3 3D Fix, getCoordinates(), getAltitude() and getMotion() return valid data

There is also a blue LED on the Bricklet that indicates the fix status.

The following constants are available for this function:

  • BrickletGPS.FIX_NO_FIX = 1
  • BrickletGPS.FIX_2D_FIX = 2
  • BrickletGPS.FIX_3D_FIX = 3
BrickletGPS.getAltitude([returnCallback][, errorCallback])
Callback:
  • altitude -- int
  • geoidalSeparation -- int

Returns the current altitude and corresponding geoidal separation.

Both values are given in cm.

This data is only valid if there is currently a fix as indicated by getStatus().

BrickletGPS.getMotion([returnCallback][, errorCallback])
Callback:
  • course -- int
  • speed -- int

Returns the current course and speed. Course is given in hundredths degree and speed is given in hundredths km/h. A course of 0° means the Bricklet is traveling north bound and 90° means it is traveling east bound.

Please note that this only returns useful values if an actual movement is present.

This data is only valid if there is currently a fix as indicated by getStatus().

BrickletGPS.getDateTime([returnCallback][, errorCallback])
Callback:
  • date -- int
  • time -- int

Returns the current date and time. The date is given in the format ddmmyy and the time is given in the format hhmmss.sss. For example, 140713 means 14.05.13 as date and 195923568 means 19:59:23.568 as time.

Advanced Functions

BrickletGPS.restart(restartType[, returnCallback][, errorCallback])
Parameters:
  • restartType -- int
Callback:

undefined

Restarts the GPS Bricklet, the following restart types are available:

Value Description
0 Hot start (use all available data in the NV store)
1 Warm start (don't use ephemeris at restart)
2 Cold start (don't use time, position, almanacs and ephemeris at restart)
3 Factory reset (clear all system/user configurations at restart)

The following constants are available for this function:

  • BrickletGPS.RESTART_TYPE_HOT_START = 0
  • BrickletGPS.RESTART_TYPE_WARM_START = 1
  • BrickletGPS.RESTART_TYPE_COLD_START = 2
  • BrickletGPS.RESTART_TYPE_FACTORY_RESET = 3
BrickletGPS.getAPIVersion()
Return type:[int, int, int]

Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

BrickletGPS.getResponseExpected(functionId[, errorCallback])
Parameters:
  • functionId -- int
Return type:

boolean

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by setResponseExpected(). For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

See setResponseExpected() for the list of function ID constants available for this function.

BrickletGPS.setResponseExpected(functionId, responseExpected[, errorCallback])
Parameters:
  • functionId -- int
  • responseExpected -- boolean

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following function ID constants are available for this function:

  • BrickletGPS.FUNCTION_RESTART = 6
  • BrickletGPS.FUNCTION_SET_COORDINATES_CALLBACK_PERIOD = 7
  • BrickletGPS.FUNCTION_SET_STATUS_CALLBACK_PERIOD = 9
  • BrickletGPS.FUNCTION_SET_ALTITUDE_CALLBACK_PERIOD = 11
  • BrickletGPS.FUNCTION_SET_MOTION_CALLBACK_PERIOD = 13
  • BrickletGPS.FUNCTION_SET_DATE_TIME_CALLBACK_PERIOD = 15
BrickletGPS.setResponseExpectedAll(responseExpected)
Parameters:
  • responseExpected -- boolean

Changes the response expected flag for all setter and callback configuration functions of this device at once.

BrickletGPS.getIdentity([returnCallback][, errorCallback])
Callback:
  • uid -- string
  • connectedUid -- string
  • position -- char
  • hardwareVersion -- [int, int, int]
  • firmwareVersion -- [int, int, int]
  • deviceIdentifier -- int

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c' or 'd'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions

BrickletGPS.on(callback_id, function)
Parameters:
  • callback_id -- int
  • function -- function

Registers the given function with the given callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickletGPS.setCoordinatesCallbackPeriod(period[, returnCallback][, errorCallback])
Parameters:
  • period -- int
Callback:

undefined

Sets the period in ms with which the CALLBACK_COORDINATES callback is triggered periodically. A value of 0 turns the callback off.

The CALLBACK_COORDINATES callback is only triggered if the coordinates changed since the last triggering.

The default value is 0.

BrickletGPS.getCoordinatesCallbackPeriod([returnCallback][, errorCallback])
Callback:
  • period -- int

Returns the period as set by setCoordinatesCallbackPeriod().

BrickletGPS.setStatusCallbackPeriod(period[, returnCallback][, errorCallback])
Parameters:
  • period -- int
Callback:

undefined

Sets the period in ms with which the CALLBACK_STATUS callback is triggered periodically. A value of 0 turns the callback off.

The CALLBACK_STATUS callback is only triggered if the status changed since the last triggering.

The default value is 0.

BrickletGPS.getStatusCallbackPeriod([returnCallback][, errorCallback])
Callback:
  • period -- int

Returns the period as set by setStatusCallbackPeriod().

BrickletGPS.setAltitudeCallbackPeriod(period[, returnCallback][, errorCallback])
Parameters:
  • period -- int
Callback:

undefined

Sets the period in ms with which the CALLBACK_ALTITUDE callback is triggered periodically. A value of 0 turns the callback off.

The CALLBACK_ALTITUDE callback is only triggered if the altitude changed since the last triggering.

The default value is 0.

BrickletGPS.getAltitudeCallbackPeriod([returnCallback][, errorCallback])
Callback:
  • period -- int

Returns the period as set by setAltitudeCallbackPeriod().

BrickletGPS.setMotionCallbackPeriod(period[, returnCallback][, errorCallback])
Parameters:
  • period -- int
Callback:

undefined

Sets the period in ms with which the CALLBACK_MOTION callback is triggered periodically. A value of 0 turns the callback off.

The CALLBACK_MOTION callback is only triggered if the motion changed since the last triggering.

The default value is 0.

BrickletGPS.getMotionCallbackPeriod([returnCallback][, errorCallback])
Callback:
  • period -- int

Returns the period as set by setMotionCallbackPeriod().

BrickletGPS.setDateTimeCallbackPeriod(period[, returnCallback][, errorCallback])
Parameters:
  • period -- int
Callback:

undefined

Sets the period in ms with which the CALLBACK_DATE_TIME callback is triggered periodically. A value of 0 turns the callback off.

The CALLBACK_DATE_TIME callback is only triggered if the date or time changed since the last triggering.

The default value is 0.

BrickletGPS.getDateTimeCallbackPeriod([returnCallback][, errorCallback])
Callback:
  • period -- int

Returns the period as set by setDateTimeCallbackPeriod().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the on() function of the device object. The first parameter is the callback ID and the second parameter the callback function:

gps.on(BrickletGPS.CALLBACK_EXAMPLE,
    function (param) {
        console.log(param);
    }
);

The available constants with inherent number and type of parameters are described below.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

BrickletGPS.CALLBACK_COORDINATES
Parameters:
  • latitude -- int
  • ns -- char
  • longitude -- int
  • ew -- char
  • pdop -- int
  • hdop -- int
  • vdop -- int
  • epe -- int

This callback is triggered periodically with the period that is set by setCoordinatesCallbackPeriod(). The parameters are the same as for getCoordinates().

The CALLBACK_COORDINATES callback is only triggered if the coordinates changed since the last triggering and if there is currently a fix as indicated by getStatus().

BrickletGPS.CALLBACK_STATUS
Parameters:
  • fix -- int
  • satellitesView -- int
  • satellitesUsed -- int

This callback is triggered periodically with the period that is set by setStatusCallbackPeriod(). The parameters are the same as for getStatus().

The CALLBACK_STATUS callback is only triggered if the status changed since the last triggering.

The following constants are available for this function:

  • BrickletGPS.FIX_NO_FIX = 1
  • BrickletGPS.FIX_2D_FIX = 2
  • BrickletGPS.FIX_3D_FIX = 3
BrickletGPS.CALLBACK_ALTITUDE
Parameters:
  • altitude -- int
  • geoidalSeparation -- int

This callback is triggered periodically with the period that is set by setAltitudeCallbackPeriod(). The parameters are the same as for getAltitude().

The CALLBACK_ALTITUDE callback is only triggered if the altitude changed since the last triggering and if there is currently a fix as indicated by getStatus().

BrickletGPS.CALLBACK_MOTION
Parameters:
  • course -- int
  • speed -- int

This callback is triggered periodically with the period that is set by setMotionCallbackPeriod(). The parameters are the same as for getMotion().

The CALLBACK_MOTION callback is only triggered if the motion changed since the last triggering and if there is currently a fix as indicated by getStatus().

BrickletGPS.CALLBACK_DATE_TIME
Parameters:
  • date -- int
  • time -- int

This callback is triggered periodically with the period that is set by setDateTimeCallbackPeriod(). The parameters are the same as for getDateTime().

The CALLBACK_DATE_TIME callback is only triggered if the date or time changed since the last triggering.

Constants

BrickletGPS.DEVICE_IDENTIFIER

This constant is used to identify a GPS Bricklet.

The getIdentity() function and the CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BrickletGPS.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a GPS Bricklet.